Build Your Own Transmitting Air Variable Capacitors!
An “eHam Classic” by David Hammack, N4DFP
Category: how to
Field Failure Database for Your Rig
W0RW shows how collecting data can expose repeating failure modes and help in correcting them.
Li Ion Battery Safety Shutdown
Keep your shack safe with a fail-safe battery charging protection systems!
Replacement of the Battery in Vacuum Tube Voltmeters (VTVM)
DL9BDM walks you through the process.